More than 25% of individuals over age 65 and 50% of individuals over age 80 suffer from varying levels of age- related hearing impairment (AHRI), and adults are losing hearing at earlier ages than in the past. Age-related hearing impairment can make it difficult to communicate and understand speech, and can lead to an overall lower quality of life. Thus it is an important public health concern. There is strong evidence that both genetic and environmental factors play a role in age-related hearing impairment. Although there have been some studies on the genetics of age-related hearing disorders, they have been on limited sample sizes and have not fully explained the heritability of the disease. A previous genome-wide association study of 1,692 individuals implicated one gene, and study of hearing thresholds on 3,417 individuals provided several candidates for further observation. Here we propose a genome-wide association study that is orders of magnitude larger than previous studies in a cohort of 100,000 individuals nested in the Kaiser Research Program on Genes, Environment, and Health. These individuals have a mean age of 63, and already have genome-wide data at over 650,000 single nucleotide polymorphisms (SNPs). We expect that with such a large cohort, we will have much more power to detect loci that affect age-related hearing loss, that may lead to discoveries of additional genes that affect hearing loss. This project provides an efficient and innovative opportunity to obtain a comprehensive understanding of how these genetic factors impact AHRI, which may help identify individuals at greater risk so they can take more preventative measures. Understanding the genetic factors will also lead to better understanding of the underlying biological mechanisms of AHRI, which may improve potential treatments.